Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
cham duc » cham soc, pham duy, phan duc
hieu van » hieu va, thien van, lieu va
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, sach thu
hanh ki » hanh vi, hanh ky, hanh kien
sac ky » cac ky, sai ky
ki su » ky su

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sac ky) or (sach ty)) nang xa hoi. hieu van ((cham duc) OR (pham duc)) van hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sac ky) OR (sach ty)) nang xa hoi. hieu van ((cham duc) OR (pham duc)) van hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sac ky) or (sach ty)) nang xa hoi. hieu van ((cham duc) OR (pham duc)) van hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sac ky) or (sach ty)) nang xa hoi. hieu van ((cham duc) OR (pham duc)) van hanh ki su triet*.